package C9_7_IntroduceNullObject;

/**
 * @author xugang1
 * @updated 2022/7/25
 * @description 引入Null对象
 */

public class PaymentHistory {
    int getWeeksDelinquentInLastYear();

    //工厂函数
    static PaymentHistory newNull(){
        return new NullPaymentHistory();
    }
}